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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: jbuckley on April 07, 2017, 01:37:19 AM

Title: what is an ethoxylated alcohol
Post by: jbuckley on April 07, 2017, 01:37:19 AM

I'm seeing that Pareth 25-9 is an ethoxylated alcohol and used as a surfactant.  What does it mean to be an ethoxylated alcohol?  Is there a specific form of alcohol associated with this substance?  Ethyl alcohol?  Isopropyl alcohol?  Something else?

In a gas chromatograph test, is Pareth 25-9 capable of being confused with ethyl alcohol?

Title: Re: what is an ethoxylated alcohol
Post by: mjc123 on April 07, 2017, 04:38:59 AM

I very much doubt it. The ethoxy group is C₂H₅O-, so the molecule is probably a long chain alcohol with one or more ethoxy substituents on the chain.

Actually, why do I say "probably"? Why not Google it? Hey presto:

"C12-15 Pareth-9 [Synonym(s): PARETH-25-9] is a polyethylene glycol ether of a mixture of synthetic C12-15 fatty alcohols with an average of 9 moles of ethylene oxide."

You could have done that.

Title: Re: what is an ethoxylated alcohol
Post by: jbuckley on April 07, 2017, 10:38:47 AM

Gee, thanks for the patronizing answer.

What you found by Googling it is a whole bunch of stuff that me, a non-chemist, doesn't understand. 

From what I remember from sophomore organic chemistry (about 30 years ago), the ethyl alcohol molecule has two carbon molecules.  I'm guessing that the 'C12-15' refers to a longer chain of carbon atoms in this molecule.

If my assumption is right, why is there a range of 12-15?  Wouldn't each of those constitute a different molecule with different properties?

Title: Re: what is an ethoxylated alcohol
Post by: Borek on April 07, 2017, 11:29:50 AM

Quote from: jbuckley on April 07, 2017, 10:38:47 AM

If my assumption is right, why is there a range of 12-15?  Wouldn't each of those constitute a different molecule with different properties?

Yes, but they are quite similar and difficult to separate, so it is easier and cheaper to use a mixture, as long as its parameters fit what we need.

Title: Re: what is an ethoxylated alcohol
Post by: sjb on April 07, 2017, 11:45:58 AM

And just to tack on to that, ethoxyethanol, for instance would be (so you have a mixture of (where R1 is your C₁₂ to C₁₅ chain and an average of 9 .CH₂CH₂O. subunits

Title: Re: what is an ethoxylated alcohol
Post by: jbuckley on April 07, 2017, 12:16:02 PM

Thanks.  These answers are really clearing things up.

Again, my organic chemistry class is far in my past.  With respect to the diagrams that sjb posted, are the lines between the respective elements/molecules representing bonds or carbon groups?

Thanks again for your help.  I think I've almost got a handle on this question.

Title: Re: what is an ethoxylated alcohol
Post by: Borek on April 07, 2017, 03:05:01 PM

Every node is a carbon atom (with as many hydrogens as necessary).